Method of cleaning a shell molded casting



Dec. 30, 1969 F. R. DUBITSKY METHOD OF CLEANING A SHELL MOLDED CASTINGFiled Feb. 23. 1967 F/Gl . 11: I. 1 in. 3 v .3 ..U.. M "WK :1 3 x g A7;; 5 a 0 United States Patent O 3,486,938 METHOD OF CLEANING A SHELLMOLDED CASTING Frank R. Dubitsky, Dearborn, Mich., assignor to FordMotor Company, Dearborn, Mich, a corporation of Delaware Filed Feb. 23,1967, Ser. No. 618,173 Int. Cl. B08b 5/00 US. Cl. 134--2 6 ClaimsABSTRACT OF THE DISCLOSURE A method of cleaning a shell molded castingto remove foreign material remaining thereon from the shell moldingoperation has the following steps. The casting is removed from the shellmold While the casting is at a temperature in the range of 1400 F. to1500 F. The casting is suspended from a support and transported on thesupport to a cleaning station Whereat a plurality of air streamsconcurrently intercept various portions of the suspended casting so thatsubstantially all of the surface area thereof is engaged by the air. Thespeed of transportation of the casting is controlled so that the castingis at a temperature in the range of 600 F. to 800 F, when it passes theplurality of air streams.

BACKGROUND OF THE INVENTION This invention relates to a method ofcleaning a casting after the casting has been formed in a shell molding.operation and, more particularly, to such a method wherein the castingis carried past a plurality of air streams which engage the same whenthe casting is at a temperature in the range of 600 F. to 800 F. wherebyany foreign material remaining on the casting is removed therefrom.

In prior cleaning processes for a casting formed in a shell moldingoperation, the casting was generally removed from the shell mold andsuspended from a suitable support on a conveyor for transportation alonga predetermined path during which time the casting would cool from atemperature initially in the range of 1400 F. to 1500 F. to roomtemperature. In the prior processes, during transportation of thecasting along the predetermined path, any sand and resin mixtureutilized in forming the shell mold which remained on the surfaces of thecasting was removed by directing a stream of abrasive particles at allareas of the shell molded casting. The small abrasive particles utilizedwith this general method were usually metal and these metal particlesare, of course, expensive when used on a high volume basis.

SUMMARY OF THE INVENTION It has been found that a casting formed in ashell molding operation may be cleaned of any retained sand and resinmixture by the method of this invention at a substantially reduced costwhen compared with prior methods of cleaning shell molded castings. Thereduction in cost is occasioned by the fact that the method of thisinvention does not employ a step wherein small abrasive Particles aredirected at the surface of a shell molded casting to remove the foreignmaterial of sand and resin therefrom. The method of this invention hasbeen predicated on the discovery that if a plurality of small airstreams are impinged upon the casting, when the casting is at atemperice ature in the range of 600 F. to 800 F., any sand and resinmixture adhering to the surface of the casting will be removedtherefrom.

The method of this invention for removing foreign material from a shellmolded casting consists of the fol lowing steps. The casting is removedfrom the shell mold while the casting is at a temperature in the rangeof 1400" F. to 1500 F. and suspended from a support which is transportedalong a predetermined path. A plurality of air streams at a singlelocation along the path are directed at the casting in such a mannerthat the air streams engage substantially all of the surface areas of acasting as it is transported along the path past the location of thestreams. The speed of transportation of the casting is controlled suchthat the ca-sting passes the location of air streams when the casting isat a temperature in the range of 600 F. to 800 F. Air engaging thecasting while the casting is at a temperature in this prescribedtemperature range results in a thorough cleaning of the surface of theshell molded casting and removal therefrom of all the sand and resinmixture adhering thereto as a result of the shell molding operation. Ingreater detail, the method of this invention employs air at a pressureof 15 to 40 p.s.i.g. with air streams positioned on both sides of thepredetermined path and spaced 3 to 6 inches from the casting conveyedalong the path.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic drawing whichshows a general arrangement of equipment utilized to perform the methodof this invention. FIGURE 2 is a schematic drawing which shows theequipment employed in the air cleaning step of the method of thisinvention as specifically applied in the cleaning of a shell moldedcrank shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of themethod of this invention will be disclosed inconjunction with themanufacture of shell molded crank shafts. However, it should be realizedthat the method of this invention is applicable to the cleaning of anycasting produced in a shell molding operation.

In the manufacture of shell molded crank shafts, as schematicallyoutlined in FIGURE 1, a shell molding operation, generally designated bythe numeral 10, is carried out wherein sand and a resin, in proportionsuch as set forth in US. Patent 2,955,336, are mixed and compacted toform the various mold portions of a shell mold. The mold portions,assembled so that the cavity thereof defines a crank shaft, are insertedinto a flask with a ferrostatic pressure resisting mass of refractorygranular material placed between the interior walls of the flask and theexterior surfaces of the shell mold thereby to support the mold in theflask. A metal selected from the group of metals consisting of malleableiron, nodular iron and grey iron is poured into a gate of the shell moldto form a crank shaft and the mold is carried along in its flask untilthe metal has cooled to a temperature in the range Of 1400 F. to 1500 F.

When the metal in the mold has cooled to 1400 F. to 1500 F., the metalis solidified and the flask containing the shell mold is overturned sothat the shell mold and the granular material placed therearound aredropped onto a grate with a force sufficient to cause a rupture of theshell mold. The crank shaft casting formed in the mold is thus at leastpartially exposed and an operator picks the casting up with a pair oftongs and suspends it from one of a plurality of supports 11 on anendless conveyor 12. At this time, the crank shaft will generally havesome of the sand and resin mixture, which forms the shell mold, adheringto various portions of the surface area thereof. Each crank shaft 13assumes a substantially vertical position as it is transported along apredetermined path by the endless conveyor 12.

As the crank shaft 13 is transported along the predetermined path, itpasses through a booth 14 wherein a pair of opposed air manifolds 16 arelocated. The manifolds 16 are shown in detail in FIGURE 2. Each manifold16 has a plurality of nozzles 17 extending therefrom, which nozzles arelong, bendable tubes formed preferably of a metal such as copper. Themanifolds 16 are connected to an air supply 18 which provides air to thenozzles at a pressure in the range of to 40 p.s.i.g.

There are sixteen nozzles 17 on each side of the crank shaft 13 and thenozzles are positioned in such a manner that as the crank shaft 13 istransported along the predetermined path, the air streams issuing fromthe nozzles will intercept various portions of the surface area thereofto cover substantially the entire surface area of the crank shaft towhich the sand and resin mixture normally adhere. The air engaging thevarious surface areas of the crank shaft is effective to removetherefrom any of the foreign material remaining on the surfaces of thecrank shaft as a result of the shell molding operation withoutdisturbing the normal, rust resistant oxide coating of the shell moldedcasting.

In accordance with the teaching of this invention, the speed oftransportation of the casting on the conveyor 12 is controlled bycontrol of a drive motor 19 which drives a conveyor drive sprocket 20 insuch a manner that the crank shaft passes between the manifolds 16 whenthe crank shaft is at a temperature in the range of 600 F. to 800 F. Ithas been found that if the casting is transported past the nozzles 17while having a temperature substantially above ambient temperature, andpreferably in this particular range, the surface of the casting iseasily cleaned of any sand and resin mixture which may have adheredthereto as a result of the shell molding operation without disturbingthe rust resistant oxide coating of the casting. While no exactexplanation of the theory of operation of this method is attempted, itis believed that when the casting is at a temperature in the range of600 F. to 800 F., the resin is easily oxidized by the air impinged uponthe surface of the casting, and once the resin is oxidized and burnedaway, it is a simple matter to carry away, in the air stream, any of thesand remaining as a contaminant on the surface of the casting.

There has been disclosed herein a method of cleaning a shell moldedcasting which is simple and efficient in operation and extremelyeconomical to utilize. The method of this invention eliminates thenecessity of employing any small, abrasive particles in cleaning shellmolded particles which under high volume conditions proves to beextremely expensive.

It will be obvious to one skilled in the art that the method of thisinvention will have many modifications thereof which fall within thetrue spirit and scope of the invention. It is intended that all suchmodifications, which are directly within the spirit and teachings ofthis invention, be construed as being within the scope of the appendedclaims.

What is claimed is:

1. The method of cleaning a casting produced from a metal selected fromthe group of metals consisting of malleable iron, nodular iron and greyiron after the casting has been formed in a shell molding operationincluding the steps of removing the casting from the shell mold whilethe casting is at a temperature in the range of 1400" F. to 1500 F.;suspending the cas ng from a s pport; and transporting the casting to acleaning station; the improvement which comprises the steps of:

directing an air stream at the casting when in the cleaning station in amanner such that the stream intercepts substantially all of the surfacearea of the casting; and

controlling the speed of transportation of the casting to the cleaningstation such that the casting is at a temperature in the range of 600 F.to 800 F. when said air stream engages the same; whereby air engagingthe casting will remove therefrom any of the foreign materials remainingon the casting as a result of the shell molding operation withoutdisturbing the normal, rust resistant oxide coating of the casting. 2.The method of cleaning a casting produced from a metal selected from thegroup of metals consisting of malleable iron, nodular iron and grey ironafter the casting has been formed in a shell molding operation includingthe steps of removing the casting from the shell mold while the castingis at a temperature in the range of 1400 F. to 1500 F.; suspending thecasting from a support; and transporting the casting on said supportalong a predetermined path; the improvement which comprises the stepsof:

directing a plurality of air streams at a single location along saidpredetermined path in a manner such that the streams concurrentlyintercept various portions of the suspended casting so thatsubstantially all of the surface area of the casting is engaged by theair; and controlling the speed of transportation of the casting suchthat the casting is at a temperature in the range of 600 F. to 800 F.when it passes the location whereat said plurality of air streams engagethe same;

whereby air engaging the casting will remove therefrom any of theforeign materials remaining on the casting as a result of the shellmolding operation without disturbing the normal, rust resistant oxidecoating of the casting.

3. The method of cleaning a shell molded casting as defined in claim 2wherein said plurality of air streams have a pressure in the range of 15to 40 p.s.i.g.

4. The method of cleaning a shell molded casting as defined in claim 3wherein a portion of the plurality of air streams are positioned onrespective sides of said predetermined path.

5. The method of cleaning a shell molded casting as defined in claim 4wherein said plurality of air streams positioned on respective sides ofsaid predetermined path are spaced from the casting transported alongsaid path at a distance of 3 to 6 inches.

6. A method of cleaning a shell molded crank shaft including the stepsof removing the crank shaft from the shell mold while the crank shaft isat a temperature in the range of 1400 F. to 1500 F.; suspending thecrank shaft from a support; and transporting the crank shaft on saidsupport along a predetermined path; the improvement Which comprises thesteps of:

directing a plurality of air streams in such a manner that the streamsconcurrently intercept various portions of the suspended crank shaft sothat substantially all of the surface area of the crank shaft is engagedby the air, said streams being positioned on respective sides of saidpredetermined path and spaced from the crank shaft conveyed along saidpath at a distance of 3 to 6 inches, and said air being at a pressure of15 to 40 p.s.i.g.; and

controlling the speed of transportation of the crank shaft such that thecrank shaft is at a temperature in the range of 600 F. to 800 F. when itpasses said plurality of air streams;

whereby air engaging said crank shaft will remove therefrom any of theforeign materials remaining on said crank shaft as a result of the shellmolding ops eration without disturbing the normal, rust resistant oxidecoating of the casting.

References Cited UNITED STATES PATENTS Evans et al 134-15 XR Marshall.

Oster 134-19 XR Howery et al. 134-33 XR Musschoot et a1. 164-270 XR 6FOREIGN PATENTS 743,184 1/ 1956 Great Britain.

MORRIS O. WOLK, Primary Examiner 5 B. S. RICHMAN, Assistant Examiner US.Cl. X.R.

